Scalable data collection for system management

ABSTRACT

A system with a local data collector that collects power management data for a subsystem. The local data collector can determine whether a first formatting associated with a first channel between the local data collector and a system power management data collector is equivalent to a second formatting associated with a second channel between the local data collector and the system power management data collector, and in response to a determination that the first formatting and second formatting are not equivalent format the power management data according to the first formatting; store the power management data formatted according to the first formatting in a first location in a memory; format the power management data according to the second formatting; and store the power management data formatted according to the second formatting in a second location the memory.

RELATED APPLICATIONS

This application is a continuation of and claims priority benefit ofU.S. application Ser. No. 14/987,968 filed Jan. 5, 2016 which is acontinuation of and claims the priority benefit of U.S. application Ser.No. 13/686,391 filed Nov. 27, 2012.

BACKGROUND

Embodiments of the inventive subject matter generally relate to thefield of power management, and, more particularly, to distributedcollection of information for power management.

Power densities of systems have been increasing with the complexity ofsystems. The increase in power density affects thermal conditions andperformance of the system. Power management of a complex system usesvarious sensors to monitor the myriad of components and subsystems andcollect information about environmental conditions and events thatimpact system performance. Power management relies on timelycommunication of this information in order to take reactive or proactiveactions to preserve performance.

SUMMARY

Embodiments of the inventive subject matter include a system thatcomprises a plurality of subsystems, a plurality of local datacollectors, and a system collector. Each of the local data collectors iscoupled with a corresponding subsystem of the plurality of subsystems.Each of the plurality of local data collectors is configured toperiodically collect power management related data from thecorresponding subsystem, and to format the periodically collected powermanagement related data for conveyance along any one of a plurality ofchannels between the local data collector and a system collector. Thesystem collector is coupled with each of the plurality of local datacollectors via the plurality of channels. The system collector isconfigured to select from the plurality of channels between the systemcollector and each of the local data collectors based, at least in part,on states of the plurality of channels, and to retrieve the powermanagement related data collected by each of the plurality of local datacollectors along a selected channel for the local data collector.

BRIEF DESCRIPTION OF THE DRAWINGS

The present embodiments may be better understood, and numerous objects,features, and advantages made apparent to those skilled in the art byreferencing the accompanying drawings.

FIG. 1 depicts a conceptual diagram of an example system with localizedpower management data collection and dynamic channel selection to carrylocal power management data.

FIG. 2 depicts an example flowchart of operations for local collectionof power management data from a managed subsystem.

FIG. 3 depicts example operations of a system power management datacollector.

FIG. 4 depicts a conceptual diagram of an example system with a localdata collector for multiple subsystems.

DESCRIPTION OF EMBODIMENT(S)

The description that follows includes exemplary systems, methods,techniques, instruction sequences and computer program products thatembody techniques of the present inventive subject matter. However, itis understood that the described embodiments may be practiced withoutthese specific details. For instance, the description refers to examplesthat collect thermal data and performance data for power management.Embodiments can collect other data, such as power consumptionmeasurements. In other instances, well-known instruction instances,protocols, structures and techniques have not been shown in detail inorder not to obfuscate the description.

A system collects information from sensors and performance monitorspositioned throughout a system to manage power consumption. The sensorsand monitors collect information from memory devices, input/outputcontrollers, graphic cores, etc. The channels that carry the informationin a typical system architecture can be insufficient to meet the demandsof timeliness for effective power management. The lack of timelinessleads to improper power management actions, which negatively impactssystem performance.

A system architecture can be designed to select a most efficient channelfrom multiple available channels to convey power management data (e.g.,a combination of thermal data and performance data). Since a complexsystem will include multiple subsystems that are subject to and/oraffect power management, data collection is localized for scalability. Alocal power management data collector collects power management data fora given subsystem at periodic time intervals. A system power managementdata collector collects the power management data from each of the localpower management data collectors at the periodic time intervals. For agiven time interval, the system power management data collector selectsa most efficient channel between the system power management datacollector and each of the local power management data collectors toobtain the local power management data. The efficiency of a channel canvary across channels because of different channel characteristics (e.g.,channel bandwidth and channel frequency) and various use and users ofthe channels. The flexibility to select a most efficient channel in agiven time interval allows power management to operate in a dynamicsystem while satisfying the demands of timeliness for power management.

FIG. 1 depicts a conceptual diagram of an example system with localizedpower management data collection and dynamic channel selection to carrylocal power management data. The depicted system includes a processorchip 101, a memory subsystem 110A, and a memory subsystem 110B. Theprocessor chip 101 includes a system power manager 103 and a systempower management data collector 105. The system power manager 103 can beimplemented with an on-chip controller. The system power manager 103performs tasks to manage power consumption across a system. The systempower management data collector 105 can be implemented with aconfigurable/programmable digital logic. Embodiments can also implementthe system power management data collector with firmware in a systempower manager or firmware executed by a processor. The system powermanager can also be implemented with firmware on a processor chip.

For this example illustration, the memory subsystems 110A and 110B havesimilar configurations. The memory subsystem 110A includes memory cells112A and an on-chip local data collector 114A. The memory subsystem 110Bincludes memory cells 112B and an on-chip local data collector 114B. Adata collector can be implemented with an on-chip controller,implemented by modifying circuitry and firmware of a subsystemcontroller (e.g., modifying a memory controller), implemented asconfigurable/programmable logic, etc. A thermal sensor 120 sensestemperature of logic at the local data collector 114A. A thermal sensor135 senses temperature of the memory cells 112A. A thermal sensor 121senses temperature of logic at the local data collector 114B. A thermalsensor 137 senses temperature of the memory cells 112B. An example of athermal sensor includes a thermal diode.

The local data collectors 114A, 114B are configured to respectivelycollect thermal data and performance data about the memory subsystems110A, 110B. For instance, each of the local data collectors 114A, 114Bis programmed with code (e.g., firmware) that instructs the local datacollector how to format and package the thermal data and performancedata collected by the local data collector. The code/digital logic forhandling thermal data for the local data collector 114A is logicallydepicted as a thermal monitor 116A. The code/digital logic for handlingperformance data for the local data collector 114A is logically depictedas a performance monitor 118A. Likewise, local data collector 114B isdepicted as including a thermal monitor 116B and a performance monitor118B. For the memory subsystem 110A, the thermal sensors 120, 135 supplythermal data to the thermal monitor 116A. For the memory subsystem 110B,the thermal sensors 121, 137 supply thermal data to the thermal monitor116B. The performance monitors 118A, 118B collect performance data.Examples of collecting performance data include reading event countersthat represent frequency of various performance related events (reads,writes, hits, misses, changes in power consumption, etc.). Anotherexample of collecting performance data includes computing inter-arrivaltimes for events (i.e., amount of time passing between events). Theperformance monitor 118A collects performance data for the memorysubsystem 110A, and the performance monitor 118B collects performancedata for the memory subsystem 110B.

Multiple channels are available to carry power management data from eachof the memory subsystems 110A, 110B to the system power management datacollector 105. A channel may be an interconnect or a bus. Examples of achannel include a serial peripheral interface interconnect bus, aninter-IC bus, a system management bus, and a point-to-point processorinterconnect. Either a channel 122 or a channel 124 can be employed tocarry power management data from the local data collector 114A to thesystem power management data collector 105. Likewise, either a channel126 or a channel 128 can be employed to carry power management data fromthe local data collector 114B to the system power management datacollector 105. When collecting power management data for the memorysubsystem 110A, the system power management data collector 105determines which of the channels 122, 124 can more efficiently provideaccess to the local power management data of the memory subsystem 110Ain a given time interval. When collecting power management data for thememory subsystem 110B, the system power management data collector 105determines which of the channels 126, 128 can more efficiently provideaccess to the local power management data of the memory subsystem 110Ain a given time interval.

The channels in FIG. 1 are depicted differently based on slightlydifferent assumptions. The channels 124, 126 are depicted aspoint-to-point channels between the system power management datacollector 105 and the local data collectors 114A, 114B, respectively.For instance, the channel 124 may be a service channel used by theprocessor chip 101 to configure a buffer chip of the memory subsystem110A, assuming the buffer chip embodies the local data collector 114A.The local data collector 114A writes collected power management datainto a memory location of the local data collector 114A (e.g., aregister file) that is accessible via the channel 124. Similarly, thelocal data collector 114B writes collected power management data into amemory location of the local data collector 114B that is accessible viathe channel 126. Before writing the power management data, however, thelocal data collectors 114A, 114B package collected thermal data andperformance data into power management data. The local data collectors114A, 114B then format the power management data as appropriate fortransfer over the channels 124, 126, respectively. When the system powermanagement data collector 105 collects power management data via thechannels 124, 126, the system power management data writes the collectedpower management data to a memory location accessible to the systempower manager 103. Although FIG. 1 depicts the channels 124, 126 aspoint-to-point between the system power management data collector 105and the local data collectors 114A, 114B, the system power managementdata collector 105 will access the channels 124, 126 with correspondingchannel controllers.

FIG. 1 depicts the channels 122, 128 with associated memories andinterconnects. The local data collector 114A writes data to a memory 131(e.g., a register file). The local data collector 114B writes to amemory 133. The local data collector 114A either writes directly to thememory 131 or via a controller for the memory 131. Likewise, local datacollector 114B either writes directly to the memory 133 or via acontroller for the memory 133. When ready to collect data, the systempower management data collector 105 will submit requests to a controllerof the channel 122 and to a controller of the channel 128. In responseto the request, the controller of the channel 122 retrieves the datafrom the memory 131. The controller then writes the data into the memory109 and notifies the requestor. In response to the notification, thesystem power management data collector 105 reads the data from thememory 109 and communicates the power management data to the systempower manager 103. Likewise, the controller of the channel 128 retrievesthe data from the memory 133 in response to the request from the systempower management data collector 105. The controller of the channel 128then writes the data into the memory 107 and notifies the requestor. Inresponse to the notification, the system power management data collector105 reads the data from the memory 107 and communicates the powermanagement data to the system power manager 103. The system powermanager 103 periodically manages power consumption/delivery to thevarious subsystems based on the data provided by the system powermanagement data collector 105.

Although FIG. 1 only depicts collection of thermal data and performancedata, embodiments can collect other data, such as power consumptionmeasurements. As an example, a power measuring device can collect powerconsumption measurement from a memory subsystem. A memory subsystem caninclude analog/digital converters of voltage across sense resistors(current measure) on power rails that supply power to memory modules aswell as measurement of supplied voltage (sensing the drop between therail and ground). Together these could be used to compute the powerconsumed from that voltage rail to the memory sub-system, at a localpower consumption monitor. Similar to the other monitors, the powerconsumption monitor, can present the power consumption measurements tothe local data collector periodically with or without modification(e.g., demarcating measurements sensed from different power rails,computing an average, etc.).

FIG. 2 depicts an example flowchart of operations for local collectionof power management data from a managed subsystem. The operations can beimplemented with firmware that programs an on-chip controller, anapplication specific integrated circuit, a programmable/configurabledigital logic controller, etc.

At block 201, thermal data is collected from a thermal monitor andperformance data is collected from a performance monitor. The monitorscan be implemented as part of a local data collector or separate codeand/or hardware. The thermal monitor obtains thermal data from one ormore thermal sensors (e.g., thermal diodes) located in the subsystemmanaged by the local data collector. If the thermal monitor collectsthermal data from multiple sensors, the thermal monitor can preserve theindividual measurements of temperature or combine the measurements(e.g., compute an average of the thermal data). The performance monitorreads a counter or counters of the subsystem of various performancerelated events that occur in the subsystem. The performance monitor mayalso compute time between events (i.e., inter-arrival event data). Thethermal data and performance data may be written to memory owned by thelocal data collector (e.g., cache).

At block 203, it is determined whether the formatting across channelsbetween the local data collector and a next level data collector (e.g.,the system power management data collector) is the same. For example,the channels may have different widths, frequencies, headerspecifications, etc. The same code may be installed into multiplesystems of varying architectures. After boot-up, the chip configured orprogrammed to operate as a local data collector (i.e., the chipexecuting the installed code) will communicate with channel controllersaccessible by the local data collector to compare formatting of thechannels. If the formatting is homogenous across channels, then controlflows to block 205. Otherwise, control flows to block 213.

At block 205, the thermal data and performance data are formatted andpackaged for power management. For example, the thermal data andperformance data are formatted to fit 8 byte registers/buffers, andidentifiers inserted to demarcate the thermal data from the performancedata. The thermal data and the performance data can be tagged by thecorresponding monitors or by the local data collector. The correspondingmonitors or the local data collector may also add error/status fieldsfor the packaged data to indicate errors for particular aspects of thedata and/or issues with the local data collection. For example, thethermal monitor inserts fields before thermal data from each thermalsensor, and the local data collector adds header fields for the powermanagement data package. The thermal monitor inserts an error flag in afield corresponding to the thermal data from a thermal sensor thatreports thermal data that substantially deviates from neighboringthermal sensors and an identifier of the thermal sensor. The local datacollector can write into the package header an offset/pointercorresponding to the field and an indication of a fault for the localdata collection. Embodiments may also encapsulate the thermal data andthe performance data for packaging. Additionally, the local datacollector may add header information to the power management data (i.e.,the thermal data and performance data) to comply with the channelspecification.

At block 207, the performance data package is written to a memorylocation accessible by the system power management data collector viaany of the channels. For instance, the local data collector writes theperformance data package (i.e., formatted and packaged thermal andperformance data). For example, the local data collector formats andpackages thermal data and performance data in memory (e.g., cache) ownedby the local data collector. The local data collector then writes thedata as formatted and packaged from the memory owned by the local datacollector to the memory accessible by any one of the channels. Thisassumes that all of the channels have access to the memory. In somecases, channels may have homogenous formatting but access to differentmemories. For those cases, embodiments may write the performance datapackage to multiple of the memories for an increased number of candidatechannels to carry the performance data package to the system powermanagement data collector.

At block 209, the memory location is marked as updated. Marking thememory location indicates tracks which locations host new data and whichhost stale data (i.e., data already communicated to the system powermanagement data collector). Examples of marking the memory locationinclude setting a flag and writing a timestamp. Control flows to block211 from block 209.

At block 211, the local data collector waits for the next time intervalto begin. Control flows from block 211 back to block 201.

If formatting across channels was determined to be heterogeneous atblock 203, then one of the channel formats is selected at block 213. Forexample, a first format may be for 8 byte register/buffers correspondingto a service channel. A second format may be 128 bytes for 128 bytecache line channels. Selection of a channel format can involve accessinga structure that indicates, literally or referentially, the differentchannel formats. The structure can be populated at system start-up.

At block 215, the thermal data and performance data is packaged inaccordance with the selected channel format. Formatting and packagingcan be done in accordance with the various examples described withreference to block 205.

At block 217, the power management data package is written to a memorylocation accessible by the system power management data collector viaone or more channels corresponding to the selected channel format.Similar to block 207, a local data collector may write the powermanagement data package to multiple memories accessible by differentchannels that correspond to the selected channel format.

At block 219, the memory location is marked as updated. Again, themarking conveys that the data is available for reading by the systempower management data collector.

At block 221, it is determined whether there is an additional channelformat that has not been selected in the current time interval. Forexample, a local data collector may walk down a linked list of channeldata format indications. When the local data collector arrives at thenull value, then all channel formats have been selected. As anotherexample, the local data collector can maintain a counter that isincremented for each selected channel format within a time interval, andreset upon expiration of the current time interval. If there anunselected channel format remains, control flows to block 223. If allchannel formats have been selected in the current time period, thencontrol flows to block 211.

At block 223, a different one of the channel formats is selected.Control flows from block 223 to block 215.

FIG. 3 depicts example operations of a system power management datacollector. The set of operations repeat for each time period, which isdefined for the system power management data collector.

At block 301, a managed subsystem is selected and the most efficientchannel for a managed subsystem is determined for a current timeinterval. A system power management data collector (“system collector”)can query each channel controller for information that indicates channelefficiency with respect to channel state and channel characteristics forchannels to a particular subsystem. For example, a first channel may beconsidered more efficient than a second channel because of greaterbandwidth (i.e., channel characteristic). But the first channel may havegreater latency (i.e., channel state) because of heavy use. Although theefficiency with respect to channel state is determined for the currenttime interval, the information indicating channel state efficiency maydescribe channel state in a previous time interval. The system collectorcan query channels for subsystems asynchronously and select a subsystemwhen all corresponding channel respond. Some embodiments prioritize thesubsystems. Thus, the system collector queries channels in accordancewith subsystem priority. For example, the memory subsystem may havepriority over the input/output (I/O) subsystem. Hence, the systemcollector queries the channel controllers of channels to the local datacollector of the memory subsystem before querying the channelcontrollers of channels to the local data collector of the I/Osubsystem. Embodiments may query all channel controllers, and thenselect channels in accordance with priority. In some cases, multiplesubsystems may have a same priority. For instance, a graphics subsystemand the memory subsystem may be defined in a time interval as having asame priority. The system collector queries the channel controllers ofchannels to both systems and collects power management data from thelocal data collector that has all channels responding.

At block 303, the most efficient channel for the subsystem is selected.For instance, the system collector selects the channel with the lowestlatency. Embodiments can input the channel state and channelcharacteristic into a function that output a value that representsefficiency. For example, the system collector may use a function thatcomputes efficiency based on both latency and bandwidth of a channel.

At block 305, a memory location is accessed via the selected channel.For example, a system collector submits a request for data to thecontroller of the selected channel.

At block 307, it is determined whether a power management data packageis available for the managed subsystem. For example, the channelcontroller reads a memory location in memory of the subsystem's localdata collector and determines whether an entry(ies) is marked as updatedby the local data collector. If a power management data package isavailable, then control flows to block 313. If a power management datapackage is not available, then control flows to block 309.

At block 309, an error is reported for the selected channel. An errorroutine can determine whether the data package is not available becauseof an error in the local data collector, a faulty monitor, a problemwith the selected channel, etc.

At block 311, the next most efficient channel for the managed subsystemis determined. A system collector can maintain the information aboutchannel states and channel characteristics for the time period or acrosstime periods. The system collector uses the maintained channelinformation to select the next most efficient channel. Control flowsfrom block 311 back to block 305.

If a power management data package was available at block 307, then thepower management data package is retrieved via the selected channel atblock 313.

At block 315, the power management data package is written to a locationaccessible by a system power manager. For instance, a system collectortransfers the power management data package to memory owned by thesystem power manager. The system collector may aggregate the powermanagement data collected across the managed subsystems. A systemcollector may also organize the collected data into suitablebuffers/memory accessible to a system power manager.

At block 317, the performance data package in the memory location of theselected channel is marked as read. The channel controller can mark thememory locations (e.g., buffers) at each end of the channel responsiveto the system collector moving or copying the performance data package.The channel controllers may mark data as read as negotiated between thecontrollers. Depending upon the channel specification, the channelcontrollers may flush the buffers after reads are performed.

At block 319, it is determined if there is an unselected managedsubsystem in the current time interval. The system collector canmaintain data that indicate the managed subsystems from which powermanagement data has been collected.

Embodiments can also design buffers in the system collector for eachmanaged subsystem. The system collector can determine whether a managedsubsystem has been selected for data collection in a current timeinterval based on whether the buffers are empty. If there is anunselected managed subsystem in the current time interval, control flowsto block 321. Otherwise, control flows to block 323.

At block 321, a different managed subsystem is selected. Control flowsfrom block 321 to block 303.

At block 323, the system collector waits until the current time intervalexpires. Control flows from block 323 to block 301.

The flowcharts are provided to aid in understanding the inventivesubject matter and are not intended to limit scope of the claims orinventive subject matter. Variations in the depicted example operationsare possible for the inventive subject matter. For example, theoperations depicted as distinct in blocks 205 and 207 of FIG. 2 mayoccur as a single operation. A local data collector may format andpackage data in the memory device that is accessible to the channels.Embodiments can format and package data in one location of the memory(e.g., a reserved scratch space) and then move/copy the formatted andpackaged data to another location in the memory when ready for access bya channel. As another example variation, additional operations can beperformed in FIG. 2 before block 211 to iterate through multiplesubsystems managed by a local data collector. Furthermore, embodimentsdo not necessarily code to accommodate the possibility of eitherhomogenous channel formats or heterogeneous channel formats. Forinstance, an embodiment can configure a local data collector to performoperations corresponding to blocks 205, 207, 209, and 211 without anydecision making operation corresponding to block 203 or the operationsof the NO branch. Similarly, an embodiment can configure a local datacollector to perform operations corresponding to the NO branch of block203 without a decision operation of block 203 and without the operationscorresponding to the blocks of the YES branch from block 203.

With respect to FIG. 3, different operations can be performed to allowfor late arrival of thermal data and/or performance data. Embodimentscan set a flag indicating a potential problem for a selected channel ofa managed subsystem and read data for a different managed subsystem.Before the time interval expires and after reading the data package forthe different managed subsystem, the system collector can try to readthe data package again from the selected channel of the managedsubsystem before reporting an error. As another example variation, asystem power manager can be notified of available power management dataafter block 315, after block 321, or after data for all managedsubsystems have been collected in a time interval.

In addition to the already described embodiments, embodiments canimplement the inventive subject matter in a hierarchical or nestedmanner. A local data collector may be responsible for multiplesubsystems. Those subsystems may or may not have their own local datacollectors, and local data collectors may be off-chip (e.g., aco−processor) and/or separate from the subsystem managed by the localdata collector. For example, an I/O hub controller may have a local datacollector that collects power management data for the I/O hub controllerand from local data collectors of devices connected to the I/O hubcontroller (e.g., a graphics device, a peripheral component interconnectdevice, etc.). These connected devices can be considered smaller domainsfor local data collection, while the encompassing or larger domainincludes these devices and the I/O hub controller. A local datacollector collects power management data from a graphics device andreports that collected data to the local data collector of the I/O hubcontroller. Another local data collector collects power management datafrom a PCIe device and also reports that collected data to the localdata collector responsible for the I/O hub controller domain. The largerdomain local data collector formats and packages the data from thesmaller domains and the I/O hub controller (i.e., formats and packagespower management data for the larger I/O hub domain). FIG. 4 depicts aconceptual diagram of an example system with a local data collector formultiple subsystems. FIG. 4 depicts a processor chip 401, local datacollectors 411, 413, and subsystems 437, 435, 433. The processor chip401 includes a system power management data collector 405 incommunication with a system power manager 403. The local data collector411 includes a thermal monitor 415 and a performance monitor 421. Thelocal data collector is coupled to a bus 439 that is also coupled withthe subsystems 437, 435. The local data collector 413 includes a thermalmonitor 417 and a performance monitor 419. A bus 441 couples the localdata collector 413 with the subsystem 433.

The local data collector 411 collects power management data from thesubsystems 437, 435. The thermal monitor 415 of the local data collector411 collects thermal data from thermal sensors 423, 427, 429. Thethermal sensor 423 senses temperature of the local data collector 411.The thermal sensor 427 senses temperature of the subsystem 437 (e.g.,near memory cells). The thermal sensor 429 senses temperature of thesubsystem 435 (e.g., a graphics processor). The performance monitor 421collects performance data via the bus 439 from the subsystems 437, 435.The performance monitor 421 can query agents of the subsystems 437, 435.The agents read/maintain counters and compute inter-arrival event times.The local data collector 411 can be configured to communicate the powermanagement data of the different subsystems managed by the local datacollector 411 as distinct or to combine the power management data. Forinstance, the local data collector can be configured (or directed by thesystem power management data collector 405) to compute an average of thethermal data across the subsystems 437, 435 and the local data collector411. Embodiments can also weigh the different data (e.g., giving greaterweight to a subsystem than the local data collector thermal data).

The local data collector 413 collects power management data from thesubsystem 433. The thermal monitor 417 of the local data collector 413collects thermal data from thermal sensors 425, 431. The thermal sensor425 senses temperature of the local data collector 413. The thermalsensor 431 senses temperature of the subsystem 433. The performancemonitor 419 collects performance data via the bus 441 from the subsystem433. The performance monitor 421 queries an agent of the subsystem 433.The agent reads/maintains counters and computes inter-arrival eventtimes.

Multiple channels are available to carry power management data from eachof the local data collectors 411, 413 to the system power managementdata collector 405. Either a channel 422 or a channel 424 can beemployed to carry power management data from the local data collector411 to the system power management data collector 405. Likewise, eithera channel 426 or a channel 428 can be employed to carry power managementdata from the local data collector 413 to the system power managementdata collector 405. When collecting power management data from the localdata collector 411, the system power management data collector 405determines which of the channels 422, 424 can more efficiently provideaccess to the local power management data in a given time interval. Whencollecting power management data from the local data collector 413, thesystem power management data collector 405 determines which of thechannels 426, 428 can more efficiently provide access to the local powermanagement data in a given time interval.

The channels in FIG. 4 are depicted differently to represent thepossibility of different channel characteristics, such as channelbandwidth. The channels 422, 426 are depicted as having greaterbandwidth than the channels 428, 424. But the channels 424, 428 mayoperate at a higher frequency, be used by fewer components, etc. Some ofthe minimal details depicted in FIG. 1 are removed from this FIG. 4. Thechannels 422, 424, 426, 428 can have buffers and controllers at thecorresponding one of the local data collectors 411, 413. Similarly, thechannels 422, 424, 426, 428 can have buffers and controllers at theprocessor chip 401. Buffers 407, 409 are depicted on the processor chip401. The buffer 407 spans both channels 422, 424. Similarly, the buffer409 spans both of the channels 426, 428. The buffers 407, 409 aredepicted with dashed lines to account for possible embodiments in whicheach buffer is actually multiple buffers and for possible embodiments inwhich the buffers are shared across the channels.

The system power management data collector 405 operates similar to thesystem power management data collector 105 of FIG. 1. The system powermanagement data collector 405 may perform additional operations on powermanagement data to separate combined power management data since powermanagement data may be combined for efficient communication from thelocal data collectors. The system power management data collector 405may tag power management data to identify the source local datacollector and/or corresponding subsystem.

Various embodiments are possible for a system power management datacollector (e.g., the collector 105 in FIG. 1) to provide powermanagement data to a system power manager (e.g., the system powermanager 103 of FIG. 1). Some embodiments configure the system powermanagement data collector to write collected power management data intoa memory accessible by the system power manager. Embodiments canconfigure the system power management data collector notify the systempower manager of when power management data is available in a given timeperiod for any one of all subsystems, for each subsystem, or for athreshold numbers of subsystems. Some embodiments configure the systempower management data collector to forward or pass the power managementdata to the system power manager directly (e.g., via an interconnect orbus in packets or messages).

Data collection, formatting and transmission actions at the local datacollector can be triggered with different techniques—through an explicitcommand sent from the system power manager/system collector (“globalcommand”) through the communication channels to the local data collectoror through a local timer function. With the global command, thecollection is synchronous to demand for the data at the power managementcontroller. Using a local timer function eliminates thecommand-transmission overhead for the data collection and also sets up adependably periodic collection-transmission process at each of the localcollectors that implement the timer function. The local data collectorscollect data in accordance with the locally produced periodic timingpulse that triggers the local data collector to collect, format, andpackage. The locally defined collection interval allows the triggeringof local data collection to be self-contained with respect to the systempower manger and/or system collector. And the locally defined collectioninterval allows local data collection to be asynchronous across localdata collectors, as well as with respect to the system collector and thesystem power manager. Embodiments can employ both techniques to initiatedata collection, formatting, and packaging within a system.Synchronization of data collection and demand for the data may be ofmore importance for certain subsystems/domains, while elimination of thecommand-transmission overhead has greater return for othersubsystems/domains.

As will be appreciated by one skilled in the art, aspects of the presentinventive subject matter may be embodied as a system, method or computerprogram product. Accordingly, aspects of the present inventive subjectmatter may take the form of an entirely hardware embodiment, an entirelysoftware embodiment (including firmware, resident software, micro-code,etc.) or an embodiment combining software and hardware aspects that mayall generally be referred to herein as a “circuit,” “module” or“system.” Furthermore, aspects of the present inventive subject mattermay take the form of a computer program product embodied in one or morecomputer readable medium(s) having computer readable program codeembodied thereon.

Any combination of one or more computer readable medium(s) may beutilized. The computer readable medium may be a computer readable signalmedium or a computer readable storage medium. A computer readablestorage medium may be, for example, but not limited to, an electronic,magnetic, optical, electromagnetic, infrared, or semiconductor system,apparatus, or device, or any suitable combination of the foregoing. Morespecific examples (a non-exhaustive list) of the computer readablestorage medium would include the following: an electrical connectionhaving one or more wires, a portable computer diskette, a hard disk, arandom access memory (RAM), a read-only memory (ROM), an erasableprogrammable read-only memory (EPROM or Flash memory), an optical fiber,a portable compact disc read-only memory (CD-ROM), an optical storagedevice, a magnetic storage device, or any suitable combination of theforegoing. In the context of this document, a computer readable storagemedium may be any tangible medium that can contain, or store a programfor use by or in connection with an instruction execution system,apparatus, or device.

A computer readable signal medium may include a propagated data signalwith computer readable program code embodied therein, for example, inbaseband or as part of a carrier wave. Such a propagated signal may takeany of a variety of forms, including, but not limited to,electro-magnetic, optical, or any suitable combination thereof. Acomputer readable signal medium may be any computer readable medium thatis not a computer readable storage medium and that can communicate,propagate, or transport a program for use by or in connection with aninstruction execution system, apparatus, or device.

Program code embodied on a computer readable medium may be transmittedusing any appropriate medium, including but not limited to wireless,wireline, optical fiber cable, RF, etc., or any suitable combination ofthe foregoing.

Computer program code for carrying out operations for aspects of thepresent inventive subject matter may be written in any combination ofone or more programming languages, including an object orientedprogramming language such as Java, Smalltalk, C++ or the like andconventional procedural programming languages, such as the “C”programming language or similar programming languages. The program codemay execute entirely on the user's computer, partly on the user'scomputer, as a stand-alone software package, partly on the user'scomputer and partly on a remote computer or entirely on the remotecomputer or server. In the latter scenario, the remote computer may beconnected to the user's computer through any type of network, includinga local area network (LAN) or a wide area network (WAN), or theconnection may be made to an external computer (for example, through theInternet using an Internet Service Provider).

Aspects of the present inventive subject matter are described withreference to flowchart illustrations and/or block diagrams of methods,apparatus (systems) and computer program products according toembodiments of the inventive subject matter. It will be understood thateach block of the flowchart illustrations and/or block diagrams, andcombinations of blocks in the flowchart illustrations and/or blockdiagrams, can be implemented by computer program instructions. Thesecomputer program instructions may be provided to a processor of ageneral purpose computer, special purpose computer, or otherprogrammable data processing apparatus to produce a machine, such thatthe instructions, which execute via the processor of the computer orother programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

These computer program instructions may also be stored in a computerreadable medium that can direct a computer, other programmable dataprocessing apparatus, or other devices to function in a particularmanner, such that the instructions stored in the computer readablemedium produce an article of manufacture including instructions whichimplement the function/act specified in the flowchart and/or blockdiagram block or blocks.

The computer program instructions may also be loaded onto a computer,other programmable data processing apparatus, or other devices to causea series of operational steps to be performed on the computer, otherprogrammable apparatus or other devices to produce a computerimplemented process such that the instructions which execute on thecomputer or other programmable apparatus provide processes forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

While the embodiments are described with reference to variousimplementations and exploitations, it will be understood that theseembodiments are illustrative and that the scope of the inventive subjectmatter is not limited to them. Many variations, modifications,additions, and improvements are possible.

Plural instances may be provided for components, operations orstructures described herein as a single instance. Finally, boundariesbetween various components, operations and data stores are somewhatarbitrary, and particular operations are illustrated in the context ofspecific illustrative configurations. Other allocations of functionalityare envisioned and may fall within the scope of the inventive subjectmatter. In general, structures and functionality presented as separatecomponents in the exemplary configurations may be implemented as acombined structure or component. Similarly, structures and functionalitypresented as a single component may be implemented as separatecomponents. These and other variations, modifications, additions, andimprovements may fall within the scope of the inventive subject matter.

What is claimed is:
 1. A method comprising: collecting, by a local datacollector, power management data for a subsystem in a system;determining, by the local data collector, whether a first formattingassociated with a first channel between the local data collector and asystem power management data collector is equivalent to a secondformatting associated with a second channel between the local datacollector and the system power management data collector; in response todetermining, by the local data collector, that the first formatting andsecond formatting are not equivalent: formatting the power managementdata according to the first formatting; storing the power managementdata formatted according to the first formatting in a first location ina memory; formatting the power management data according to the secondformatting; and storing the power management data formatted according tothe second formatting in a second location the memory.
 2. The method ofclaim 1 further comprising: marking the first memory location asupdated; and marking the second memory location as updated.
 3. Themethod of claim 1 further comprising: in response to determining, by thelocal data collector, that the first formatting and second formattingare equivalent: formatting the power management data according to thefirst formatting; and storing the power management data formattedaccording to the first formatting in a third location in the memory. 4.The method of claim 3 further comprising marking the third memorylocation as updated.
 5. The method of claim 1, wherein collecting thepower management data comprises: collecting thermal data from thermalsensors that sense temperature throughout the subsystem; and collectingperformance data about the subsystem.
 6. An apparatus comprising: asubsystem; a memory; and a local data collector configured to: collectpower management data for the subsystem; determine whether a firstformatting associated with a first channel between the local datacollector and a system power management data collector is equivalent toa second formatting associated with a second channel between the localdata collector and the system power management data collector; inresponse to a determination that the first formatting and secondformatting are not equivalent: format the power management dataaccording to the first formatting; store the power management dataformatted according to the first formatting in a first location in thememory; format the power management data according to the secondformatting; and store the power management data formatted according tothe second formatting in a second location the memory.
 7. The apparatusof claim 6, wherein the local data collector is further configured to:mark the first memory location as updated; and mark the second memorylocation as updated.
 8. The apparatus of claim 6, wherein the local datacollector is further configured to: in response to a determination thatthe first formatting and second formatting are equivalent: format thepower management data according to the first formatting; and store thepower management data formatted according to the first formatting in athird location in the memory.
 9. The apparatus of claim 8 wherein thelocal data collector is further configured to mark the third memorylocation as updated.
 10. The method of claim 6, wherein the local datacollector is further configured to: collect thermal data from thermalsensors that sense temperature throughout the subsystem; and collectperformance data about the subsystem.
 11. A computer program product forscalable data collection, the computer program product comprising: acomputer readable storage medium having computer usable program codeembodied therewith, the computer usable program code configured to:collect power management data for the subsystem; determine whether afirst formatting associated with a first channel between the local datacollector and a system power management data collector is equivalent toa second formatting associated with a second channel between the localdata collector and the system power management data collector; inresponse to a determination that the first formatting and secondformatting are not equivalent: format the power management dataaccording to the first formatting; store the power management dataformatted according to the first formatting in a first location in thememory; format the power management data according to the secondformatting; and store the power management data formatted according tothe second formatting in a second location the memory.
 12. The computerprogram product of claim 11, the computer program code furtherconfigured to: mark the first memory location as updated; and mark thesecond memory location as updated.
 13. The computer program product ofclaim 11, the computer program code further configured to: in responseto a determination that the first formatting and second formatting areequivalent: format the power management data according to the firstformatting; and store the power management data formatted according tothe first formatting in a third location in the memory.
 14. The computerprogram product of claim 13, the computer program code furtherconfigured to mark the third memory location as updated.
 15. Thecomputer program product of claim 11, the computer program code furtherconfigured to: collect thermal data from thermal sensors that sensetemperature throughout the subsystem; and collect performance data aboutthe subsystem.